Documentary photography of ethnic minorities

A, A is Liaoning Province, and Changbai Mountain in the southeast is rich in precipitation, belonging to humid areas.

B, in the picture, B is Yunan Province, and the west is the Hengduan Mountains running through the north and south in China. Therefore, b does not meet the meaning of the question;

6.c is Heilongjiang province, because of its high latitude and cold and humid climate.

4. The least number of ethnic minorities in China is Zhuang, about 1 to 220,000, mainly distributed in Ding Province-Guangxi Zhuang Autonomous Region.

So, choice: four.